We describe herein a program directed at the total synthesis of representatives of three widely divergent classes of pharmacologically active substances-ionophore antibiotics, prostanoids, and steroids-utilizing the intramolecular Diels-Alder cycloaddition as a common key step. Antibiotic X-14547A is a novel, recently isolated ionophore antibiotic showing in vitro activity against Gram-positive bacteria and activity as a growth promotant for ruminants. X-14547A is unusual among the ionophore antibiotics in that it transports both uni- and divalent cations across an immiscible solvent barrier. The historical and future applicability of steroidal and prostanoidal agents to clinical problems needn't be trumpeted here. The structural complexity of these compounds together with the demonstrated heightened importance of analog preparation for the modification of the biological responses triggered makes prostanoids and steroids targets of major importance for practitioners of total synthesis. We intend to demonstrate the power and versatility of the intramolecular Diels-Alder reaction in short, versatile and highly stereoselective syntheses of clinically active agents of highly varying structural types. The syntheses are designed to provide access to a @ide range of structural analogs for testing. It is intended that such compounds will be provided and submitted as the logical conclusion of the program.